In a network having two subscribers A and B, each connected to a data network, e.g. the Internet, e.g. by means of a leased line or a dialup connection. Subscriber A sets up a telephone connection to subscriber B. In the course of the telephone connection, in addition to the voice information, data, e.g. multimedia data, also need to be transferred between subscriber A and subscriber B.
In this type of network, it is difficult to find a suitable method which allows not only the telephone connection between two or more subscribers, but also a data network connection to be set up automatically between these subscribers upon request, whose configuration is automatically aligned with changes in the configuration of the telephone connection.
One known method involves all the subscribers knowing their data network addresses (e.g. IP addresses), exchanging them orally over the telephone connection and configuring their data terminal equipment accordingly. This is laborious for the subscribers, however, and presupposes knowledge about the way in which the data network works. It is not possible to set up a data network connection to an existing telephone connection automatically. Similarly, all the configuration changes have to be made manually.
Another known method uses the option of the subscribers registering with a central server in the data network, where an (imaginary) name for the subscribers is linked to their data network address. A data network connection can then be set up using the subscribers' (imaginary) names. This method is also unable to set up a data network connection automatically in addition to an existing telephone connection or to align the configuration of the data network connection with an altered configuration of the telephone connection.
In another known method, the subscribers' telephone equipment and data terminal equipment are connected to one another and, when the data network connection is set up, the data terminal equipment transfers the connected telephone equipment's telephone number together with the data terminal equipment's data network address to a central database. If a data network connection is required in addition to the telephone connection, the telephone equipment first transmits the other subscriber's call number to the data terminal equipment. The data terminal equipment can take the necessary data network address from the central database. A drawback in this context is the connection which is required between the telephone equipment and the data terminal equipment, and furthermore, this method often cannot automatically align the data connection (e.g. when no ISDN connections are involved) upon call forwarding, call transfer, conferencing and other changes in the configuration of the telephone connection.